I've had trouble with the "newer" air-brakes,as well. I had a right-front S-cam "rotate",and lock-up,but that was AFTER standing on the pedal with both feet,and pulling both the "Stops". Still ran the red-light doing 35 M.P.H.,and then catching fire(hot hub-grease).Yes,I released the brakes,but the S-cam didn't "Lock" the wheel,but caused enough friction to cause a hub-fire. 6-months later,a fellow driver lost the brakes in the same truck,and rolled it at the bottom of a long hill. luckily,the windshield popped-out,because he "Ran",with one foot out the windshield-frame,and one foot in the window,until it stopped! If you "run" with air-brakes,make sure you keep the system free of water. If it's humid,drain your tanks every chance you get. Better yet-invest in an air-dryer.
